Coping with unreliable ISP mail services

One of the biggest pains in taking on a new client is connecting them up to their Internet Service Provider. The initial dial-up is straightforward enough, but ISPs end to have difficulty providing a reliable and comprehensive email service. You'd have thought they'd have got the hang of it by now, but some of them seem to be getting worse!  If there's only one user collecting mail their POP3 box is probably sufficient, but if it gets more complicated than than that - which it always is - they seem to have difficulties:

For example you might think that most mail is sent to the person named in the 'To:' header, but that header is optional, or may even contain fake addresses - what matters are the recipient addresses in the SMTP headers, and ISPs are remarkably careless in their handling of this crucial information. Looking for an example of  these fake 'To:' headers? Look no further than mail sent from distribution lists.

Many of the ISPs who have managed to cope with issues like that suffer from other email ailments. Some have been increasingly suffering from capacity problems, leading to delayed and duplicated mail.

So how do you work around these problems?

First of all, you don't need to use the same ISP for email as you do for dial-up. Play to their individual strengths.

In fact, outbound email doesn't need to go via an ISP at all. You can configure Mailtraq to send email directly to the destination machine (technically, a Mail  eXchange, or MX machine). Your dial-up ISP will see the packets going over their network, but not get involved in sending (or delaying) them.

See this page for more information on configuring Mailtraq to send mail in this way http://www.mailtraq.com/KB00030302.html

There are lots of options when it comes to getting inbound email without your ISP being involved. Which option is best depends on whether your client has a permanent connection or not.

If they do have a permanent connection, you can get people to send email directly to their Mailtraq machine. You do this by setting the MX record of their domain to the public-facing IP address of the machine Mailtraq is running on. Naturally they'll need a static IP address for this to work.

If they don't have a static IP address, or don't have a permanent connection, you can use a third-party ISP, and collect mail from them every so often. You could do this using POP3, but the best way to collect is via SMTP as Mailtraq will then get the SMTP envelope - the bit that says who the mail is really for (as the 'To:' header isn't going to help us).

Unfortunately the standard SMTP protocol has a problem here, as it's a 'push' protocol (which is to say the machine sending the email to you starts the connection) It's got two problems here: it doesn't know when to send it (you could be offline) and it doesn't know where to send it (your IP address could change each time you dial up)

All is not lost, however, as Mailtraq provides a couple of new protocols, ETRN and ODMR, to perform this 'Reverse SMTP' trick.

For more information on setting this up: see the Mailtraq online help file - search for 'ODMR', 'ETRN', or 'Reverse SMTP'